Ammonium-nitrate explosive



- the sensitivenesc-s as HALTER 0. SNELLING, 0F ALLENTOWN,

POWDER COMPANY, OF NEW YORK, N.

PENNSYLVANIA, ASSIGNOR TO TROJAN Y., A CORPORATION OF NEW YORK.

AMMONIUM-NITRATE EXPLOSIVE.

it 0 Drawing.

T 0 all whom it Be it known may concern: that I, WALTER O. Snnntmo, a citizen of the United States and resident of Allentown, Lehigh county, Pennsylvania, have invented certain Improvements in Ammonium- Nitrate Explosives, of which the following is a specification.

My invention relates to ammonium nitrate explosives, and its object is the production of such an explosive of high brisan'ce, and one which while having a relatively high content will not cake either during manufacture or after long storage. My invention further relates to ammonium nitrate explosives in which nitro-starch is employed, in relatively small amount, as a sensitizer.

Explosives containing ammonium nitrate and nitro-starch have heretofore been employed but in all such explosives previously made or suggested, either the ammonium nitrate has been a minor xplosive constituent, present in amounts of 30% or 40% only, the primary explosive agent present being the nitro-starch, or a mixture of nitro-starch and an inorganic nitrate such as sodium nitrate, or else the explosive has been of the class known as ammonium nitrate metallic explosives in which a metal or metallic ingredient such as aluminum has been employed to raise the temperature of combustion and act as a quickening agent, an which explosives are used in compressed form. In my explosive, no metallic ingredient is employed, the explosive is in pulverulent form and remains so, and so far as I am aware I am the first to produce an ammonium nitrate nitro starch explosive of this type, in which the ammonium nitrate is the primary explosive present in relatively high content and the nitro-starch in relatively low content.

In mixtures of ammonium nitrate and nitro-starch, in which there is a high ammonium nitrate content, there is a tendency to set to a firm cake after standing for some time, as the result of a recrystallization of the ammonium nitrate, this recrystallization being due in part to a small initial moisture content of the ammonium nitrate and in art to small amounts of moisture takenup 1n the course of the manufacture of the ex. plosive. This setting or caking decreases the explosive and Specification of Letters Patent.

Application filed. January 1%,

ing that direct contact mixture.

Patented June 1920.

1919. Serial No. 271,175.

terferes with loading operations. I have discovered that if the ammonium nitrate crystals be coated with very finely divided particles of a pulverulent agent, the direct contact between the crystals and ammonium nitrate which is necessary before recrystallization and setting can occur, can be prevented. I

Where the nitro-starch constitutes not less than approximately 20% of the mixture and is thoroughly mixed with the ammonium nitrate, constituting not less than approximately 50% of the mixture, the nitro-starch itself can act in the double capacity of a sensitlzer and a pulverulent agent for maintainmg separate the crystals or grains of ammonium, nitrate and accordingly I have discovered thatit is entirely practicable to produce ammonium nitrate-nitro -starch explosives with high ammonium nitrate content and relatively low nitro-starch content, and'to produce and maintain said explosive 1n uncompressed pulverulent form.

\Vith explosives made according to my present invention and using proportions of ammonium nitrate in excess of 50% of the total, and nitro starch in the proportion of less than 20% of the total, I find that it is desirable to add a further agent to assist in keeping apart the crystals of nitrate of ammonia and to prevent the mass setting or caking by the recrystallization of the ammonium nitrate. For this purpose I may use any pulverulent material of high covering power such for example as p0wdered iron oxic (ochre or rouge). It will be understood that such added constituent of high covering power is explosively inert and that its sole function is the keeping apart by coating them with very finely divided particles of the agent, and thus preventbetween the crystalswhich leads to setting or caking. Nitrostarch can act successfully as a sensitizing agent when present in as small an amount as 5% of the total quantity of the explosive, but in such case it is necessary, in order to prevent caking, to add the additional pulverulent agent in an amount constituting approximately 15% of the total The particles of nitro-starch and the additional pulverulent material are caused to be thoroughly interspersed among the ammonium nitrate particles, and the direct adhesion of these particles to each other is thereby prevented.

An illustrative formula for nitro-starch explosive containing iron oxid for the purpose stated is the following:

Nitro-starch 12.0 mmonium nitrate 60.0% Sodium nitrate 18.0% Hydrocarb n oi1 20% Iron oxid (rouge)i 8.0%

In making up explosives containing nitrostarch, ammonium nitrate and the finely'dr vided covering material, other ingredients heretofore used in making up nitro-starch powders may be added, as illustrated in the formula, and as will be readily understood, and the relative proportions of nitro-starch, ammonium nitrate and pulverulent ingredie'nt can be varied within limits to produce explosives of the varying specific characteristics. l: have obtained useful results with mixtures employing nitro-starch from 5% to ammonium nitrate from 40% to 90%, and iron oxid from 2% to 15%, the percentages given being percentages of the entire explosive mixture.

Uther finely divided materials of high covering power which I have successfully employed for the purpose stated, are powdered talc, and powdered silica. These ingredients give a high degree of non-inflam mability, and it will he understood that other equivalent finely divided inert material may be employed. TV here absolute non-inflammability of the finished explosive is not necessary, I have found finely divided charcoal and ordinary starch to give satisfactory results.

So far as 1 am aware, I am the first to discover that ammonium nitrate-nitrostarch explosives can be made in which the ammonium nitrate is the primary explosive agent, and the explosive maintained in pulverulent form, and to discover that caking can be avoided by the coating of the ammonium nitrate particles with a pulverulent agent, either the nitro-starch itself, when present in an amount as great as 20% or more, or

the nitro-starch and an additonal inert pulverulent material, when the nitro-starch constitutes less than 20% of the entire mixture.

claim:

1. An explosive containing ammonium nitrate in excess of 40% of the entire mixture, nitro-starch and a finely divided material of igh covering power interspersed among the particles of said ammonium nitrate.

2. An explosive containing ammonium nitrate, constituting from 40% to 90% of the entire mixture, nitro-starch, and a finely divided material of high covering power interspersed among the particles of said ammonium nitrate.

8. explosive in non-caked pulverulent form containing nitro-starch 5% to 20% and ammonium nitrate from 40% to 90% of the entire mixture.

4. An explosive in noncal ed pulverulent form containing nitro-starch 5% to 20% and ammonium nitrate from 40% to 90% of the entire mixture, and a finely divided material of high covering power interspersed among the particles of said ammonium nitrate.

5. An explosive containing nitro-starch 5% to 20%, ammonium nitrate from 40% to 90% of the entire mixture, and an additional finely divided material of high covering power interspersed among the particles of l arimonium nitrate, said finely divided material comprising 2% to of the entire explosive.

6. An explosive containing ammonium nitrate constituting from 40% entire mixture, nitro-starch and powdered iron oxid interspersed among the particles of said ammonium nitrate.

7. An explosive containing ammonium nitrate 40% to 90% of the entire mixture, nitrostarch 5% to and powdered iron oxid interspersed among the particles of said ammonium nitrate.

8. Ali-explosive containing ammonium nitrate to 90% of the entire mixture; nitro-starch from to 20%, and powdered iron 'oxid thoroughly mixed with said ammonium nitrate, said iron oxid comprising 2% to 15% of the entire explosive.

9. in explosive comprising ammonium nitrate nitro-starch 12%, sodium nitrate 187;, hydrocarbon oil 2% and iron oxid 8%.

WVALTER O. SNELLING. 

